1. Technical Field
The present invention relates to a packet communication method, a packet communication system, a wireless terminal, and a packet communication device. The invention is preferable for use in, for example, packet communication in a next generation network.
2. Description of the Related Art
In the 3GPP, a next generation system (Release 8) which can accommodate various kinds of existing wireless access methods (access networks) and make core networks all-IP (All IP) networks is taken into consideration. The contents are described in the 3GPP TS 23.401 V1.2.1.
The next generation architecture taken into consideration here is called Systems Architecture Evolution (SAE). The wireless technique in the SAE is called LTE (Long Term Evolution).
In chapter 5.5.2.1 of the 3GPP TS 23.401 V1.2.1, the processing of a user terminal (UE: User Equipment) handing over from E-UTRAN (Evolved Universal Terrestrial Radio Access Network) to UTRAN in the SAE (E-UTRAN to UTRAN Iu mode Inter RAT (radio access technology) handover based on PS (Packet Switched) handover) is described. The E-UTRAN is described in the 3GPP TS 36.300 V8.2.0.
Japanese Laid-Open Patent Publication No. 2005-529554 discloses a technique about packet flow processing in a communication system. In this description, a resource reservation protocol (RSVP: Resource reSerVation Protocol) message includes information of a packet flow parameter for use in determining a packet flow processing method. The packet flow parameter information includes, for example, QoS (Quality of Service) of a packet flow and a header compression type to be used in the packet flow (for example, refer to the paragraphs 0051 to 0058 of Japanese Laid-Open Patent Publication No. 2005-529554).
One of the objects of the invention is to make it possible to continue processing according to a predetermined compression or decompression method before and after handover (HO) of a wireless terminal between different access networks.
Another object is to restrain from decreasing efficiency of resource use in a wireless zone between a wireless terminal and a wireless access network.
The invention is not defined by or restricted to the above objects but various functions and effects derived from each structure shown in the embodiments described later, that is, the functions and effects which cannot be obtained in the conventional technique can be defined as further objects.